1 / 15

Simulation of detection of gamma radiation by germanium detector

Simulation of detection of gamma radiation by germanium detector. Courtine Fabien Equipe Thermoluminescence Laboratoire de Physique Corpusculaire Clermont-Ferrand courtine@clermont.in2p3.fr. Introduction.

Download Presentation

Simulation of detection of gamma radiation by germanium detector

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Simulation of detection of gamma radiation by germanium detector Courtine Fabien Equipe Thermoluminescence Laboratoire de Physique Corpusculaire Clermont-Ferrand courtine@clermont.in2p3.fr MGS meeting

  2. Introduction • Measurement of gamma activity of solid or liquid samples in an energy range from 20 keV to 3 MeV dosimetry • 2 geometry : well and marinelli MGS meeting

  3. Problematical • Efficiency calibration of a germanium detector • Efficiency = nb gamma photopeak/nb gamma emitted • No available calibrated source to cover all the energy range • Correction of self-attenuation • Cascade effect • Calibration fully experimental impossible MGS meeting

  4. Method • Monte Carlo calculations need full knowledge of geometry, which is not the case • Calibration needs to be a combination of experimental measurements and Monte Carlo calculations: unknown dimensions are calculated by comparing simulated and experimental efficiency • Experimental measurements done with two point-like sources (137Cs et 60Co) displaced inside the detector’s well MGS meeting

  5. Experimental measurements • 137Cs E = 32 keV 137Cs E = 662 keV MGS meeting

  6. Experimental measurements • 60Co E ~1250 keV MGS meeting

  7. Model • Efficiency simulated with geometry given by Canberra manufacturer • 137Cs E = 32 keV 137Cs E = 662 keV MGS meeting

  8. Model • 60Co E ~ 1250 keV MGS meeting

  9. Model • Introduction of two inactive layers in model • Size of these layers is determined by successive adjustment between experimental and silmulated efficiency • Internal inactive layer thickness calculated with low energy gamma (32 keV) • External inactive layer thickness calculated with higher energy gamma (662 keV) MGS meeting

  10. Results • 137Cs E = 32 keV 137Cs E = 662 keV MGS meeting

  11. Results • 60Co E ~ 1250 keV MGS meeting

  12. Interpretation • Physical meaning of inactive layers ? • 2 effects: • Electrical field effect  Mgs (cortesy of C. santos, P. Medina, C. Parisel), passive area MGS meeting

  13. Interpretation • Lithium diffusion on external face and bore implantation on interne face dead layer • Good agreement simulation-experience at low and mean energy but disagreement at high energy : • E = 32 keV R = (0.992+/-0.006) • E = 662 keV R = (0.997+/-0.002) • E = 1250 keV R = (0.925+/-0.001) MGS meeting

  14. Tools • Geant4 : simulation of the passage of particles throught matter • Advantages : • Cross sections validited at low energy • Complex geometry like boolean operation or shapes with hole. • Geant4 is written in C++ • Possibility of use many package for analyse and graphical interface (Root, OpenScientist, Aidda…) • Disadvantages : • Need to know C++ • No graphical interface already built • No package for analysis MGS meeting

  15. Tools • Gate : user interface over Geant4 • Advantages : • Language (script) which doesn’t need the knowledge of C++ • Easy to use • Disadvantages : • No possibility to make geometry as complex as in Geant4 • No graphical interface • No package for analysis MGS meeting

More Related